Electron gun particle barrier formed by plurality of flexible radial sectors



United States Patent Ofi ice 3,183,383 Patented May 11, 1965 ELECTRON GUN PARTICLE BARRIER FORMED BY PLURAILITY OF FLEXELE RADIAL SECTGRS Frederick H. Townsend, Elmira, and Lawrence GJHealy,

Horscheads, N.Y., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 12, 1960, Ser. No. 21,658

3 Claims. (Cl. 313-82) This invention relates to an improved electrode assem* bly and more particularly to an improved means for supporting and mounting an electrode assembly within an envelope.

The principles of this invention are embodied in an electrode assembly of a vidicon type camera tube which includes a tubular envelope with an electron gun positioned therein. The electron gun is comprised of a plurality of tubular electrodes which normally extends substantially the entire length of the tubular envelope and is mounted substantially from the base end of the envelope. It is therefore normally necessary to provide additional means to support and locate the electron gun Within the bulb at a remote position from the base. The vidicon is also provided with a photoconductive target at the remote end of the envelope with respect to the base. It is known that blemishes on the target surface of the vidicon are often caused by small particles of loose material which originated at the base end of the gun from the ceramic mounting rods, the heater or the getter structure and migrated or fell onto the target damaging the photoconductive material.

There are many known methods of supporting and positioning the electron gun within the tubular envelope and the customary way of doing this in the industry with regard to the vidicon type camera tube was utilizing a plurality of spaced spring fingers near the remote end of the electron gun with respect to the base. The spring fingers were of flexible material and pressed against the inner surface of the wall of the tubular envelope to support and position the electron gun. This type of mounting however did not solve the problem of foreign particles migrating from the base end of the tube into contact with the photoconductive target. In order to solve this problem, one solution proposed has been the utilization of an annular ring mounted around the forward end of the electron gun. This ring was referred to as a dustshield and was comprised of a short cylindrical portion which served as a means of mounting the dust shield to a tubular electrode of the electron gun. A conical portion or flange extended backwardtoward thebase and was formed in such a manner that it fit closely all around the inner surface of the bulb'wall thus providing an impassable barrier to dust particles and at the same time providing a supporting and a positioning member between the gun and the bulb envelope.

The dust shield type construction prevented migration of foreign particles from the base to the target inthose 2 vibrated during operation, the effects of low frequency rnicrophonics were often very noticeable;

Accordingly, an object of this invention is to provide an improved mounting and support means for electrode assembly.

It is another object to provide improved means for sup- I porting an electrode assembly within a container and prevent migration of foreign particles the tube to another section.

It is another object to provide improved means for mounting and supporting an electrode, said means being adapted to absorb vibration by frictional means provided within the supporting means.

Still another object is to provide an improved electron gun and means for mounting the same within an electron tube envelope.

These and other objects are effected by the invention as will be apparent from the following description taken in accordance with the accompanying drawings throughout which like reference characters indicate like parts, and in which:

FIGURE 1 is an elevational view partly in section of a vidicon including the electrode assembly embodying the principles of the invention; a v

FIG. 2 is an end elevational view of the support ring in the process of manufacture embodying the principles of theinvention; I

FIG. 3 is a side view of the support ring shown in F1622;

FIG. 4 is an end elevational view of the support ring from one section of illustrated in FIG. 1'; and 7 'FIG. 5 is a sectional view taken along line V--V of Referring now in detail to FIG. 1, there is shown a vidicon tube having an envelope comprising a tubular bodyportion 10 of glass formed fromcylindrical tubing. The tubular member 10 is closed at one end by, arbase member or button stem 12 through whichthe 'lead-in members-are sealed and provide electrical connectionto 'the'electrodes of an'ele'ctron gun 30 provided within the envelope and also provide mechanical supportfonthe electron gun 30 within the tubular envelope. The oppoa site end of the tubular body 10 is closed by a flat glass face plate 14 with a contact ring 16 disposed therebetween and sealed thereto. A thin layer 18 of electrical conductive material is deposited onthe inner surface of the face i plate 14 and is connected to'the conductive ring 16. A 7

' type and consists of a plurality of tubular electrode 'memcases where the dust shield was accurately dimensioned with respect to the inner surface of the bulb wall. It is found that in order to insure a dust tight fit it is necessary that the internal bulb diameter be held to very close limits.

This requires the use of precision bore redrawn or man drel shrunk tubing for the bulb with consequent appreciable increase in bulb cost. If one used normal machine the envelope would often produce a rattling of the electron gun within a tube and if the tubes were tapped or bers'with diaphragm members and apertures therein for forming, controlling and'dir ecting'the electron beam onto the target 20." a I In the specific embodiment shown in FIG. 1, a control grid 31 is shown comprised of a'tubular member'32'having a diaphragm closing oif the endof the tubular member 32 facing the photoconductivetarget'20." The dia 'phragm isprovidedwith ac'entrally located' aperture.

Positioned within "this cup-shaped control grid 31 is a cathode. The cathode includes' heaterfheans for heating the cathode member to emission temperature. A screen grid 37 is provided on the side 'OfJthe control grid 31 facing the target member 20 and is provided with a tub'ular member 38 with a diaphragmhaving an aperture there- .39 is next provided between the screen grid 37 and the target 20 and is also tubular in shape with a portion 44 thereof adjacent the screen grid 37 of similar diameter as the tubular portion of the'screen grid 37 and the remaining portion 46 of the accelerating electrode of a larger diameter within an intermediate flared'connecting portion 48. Positioned at the end of the electrode 39 facing the target 20 is a reenforcement ring 50 with an outwardly extending flange portion 52 and three tab extensions 54 from the flange 52 and extending towards the base as illustrated in FIG. 1. A collector grid having a mesh 56 of about 500 wires per inch and having a supporting ring 58 about its periphery is attached to the flange 52 of the reenforcernent ring 50 and is also provided with extending tabs 60 which extend toward the base and are welded to the tabs 54 on the reenforcement ring 50 as indicated in FIG. 1.

The control grid 31 is supported from the base by leadin members welded to the tubular portion 32 and in addition the grid 31 is provided with three insulating support rods 41 spaced about the periphery and extending parallel to the axisof the electrode structure and secured to the grid by connectors 43. The insulating rods 41 extend forward and are in turn securedto the tubular portion 38 of the screen grid 37 and the smaller diameter portion 44 of the accelerating anode 39 in a similar manner by connectors 43 to thereby support the screen grid 37 and accelerating anode 39 within theenvelope from the base. The electron gun 30 is thus formed in a unitary structure.

The electron gun 30 is also supported near the target 7 end of the envelope by a support member 61 consisting of a tubular base portion 62 and a plurality of outwardly extending spring fingers 63. The inner diameter of the tubular base portion 62 is slightly greater than the outer diameter of the larger portion 46 of the electrode 39 and is positioned thereon and secured by welding near the target, end of the electrode 39. The-outer ends of the spring fingers 63 are flexed and bear against the inner surface of the wall of the envelope 10. a The support member 61 may be fab'ricatedin a manner shown in FIG. 2 by providing a tubular member 62 having an outwardly extending flange 65 with the flange portion 65 cut along radially extending lines 67 so as to provide a plurality of radially extending flange sectors 63. When the electron gun 30 is inserted into the envelope, the flange sectors 63 are flexed rearwardly toward the base portion 62 such that the sectors 63 overlap and engage theadjacent sectors 63 providing frictional contact between adjacent sectors 63. The structure of the support member 61' after insertion into the envelope is shown in more detail in FIGS. 1, 4 and 5. The support member 61 may be of any suitable material such as a nickel chrominum alloy having a thickness of about 7.003 inch and the outer diameter of the flange 65, that is prior to insertion into the envelope, as illustrated in FIGS. 2 and 3 is such as to be vslightly larger than the inner diameter of the largest bulb with which it may be used. This ensures that when the gun carrying the support 61 is inserted into the bulb, the sectors 63 of ,the flange 65'are forced into greater overlap.. The smaller the internal diameter of the bulb the greater will be the degree of overlap of-the sectors '63. The degree of overlap possible .is such that bulbs varying in diameter by as much as .04 inch can be fitted intimately by the self-adjusting sector flange.

over each other and because of the divided nature of the flange 65,it forms itself to the shape of the bulb even if the bulb is slightly oval. Thus, a complete barrier is maintained between the migration of dust particles from or partial shock absorbing mounts. It is also obvious that illustration of the fabrication of the device is only given as an example and any other suitable method of fabrication may be utilized. Another important feature is that the overlap of the sectors is also in intimate contact between adjacent sectors so that the sectors slide over each other with a considerable amount of friction. This friction is enhanced by the restraining elfect of the bulb wall on the sectors. This provides means whereby any resonance which might be induced by vibration is heavily damped and is consequently not self-sustaining.

While the present invention has been shown in only one embodiment, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications Without departing from the spirit thereof. t

I claim as my invention:

1. An electron discharge device comprising a tubular envelope and an elongated electron gun comprising a plurality of tubular electrodes positioned within said tubular envelope, the outer diameter of said tubular electrodes less than the internal diameter of said envelope thereby defining an annular region, means for supporting said electron gun and closing off said annular region to prevent passage of particles, said means comprising a tubular member of resilient sheet metal having a flange portion,

" said tubular member having its inner'surface secured to the outer surface of .one of said electrodes with'said flange portion extending outwardly from the outer surface of said electrode, the other diameter of said flange portion when perpendicular to said electrode being greater than the internal diameter of said envelope, said flange portion comprised of a plurality of radial sectors so that when said electron gun is inserted into said envelope, said flange sector portions are flexed to overlap and provide a barrier portion with respect to passage of particles and substantially all of the outer periphery of said flange resiliently engages the inner surface of said envelope supporting said electron gun within said envelope.

2. An electron discharge device comprising a tubular envelope and an elongated electron gun comprising a plurality of tubular electrodes positioned within said tubular envelope, the outer diameter of said tubular electrodes less than the internal diameter of said envelope thereby defining an annular region, means for supporting said electron gun and providing a barrier in said annular region to prevent passage of particles therethrough, said means comprising a tubular member of resilient sheet metal having a flange portion, said tubular member secured to the outer surface of one of said electrodes with said flange portion Because :6

' the overlapping surfaces of the sectors 63 move closelyextending outwardly from the outer surface of said electrode, the outer diameter of said flange portion being greater than the internal diameter of said envelope, said flange portion provided with a plurality of. radial sector portions so that when said electron gun is inserted into said envelope, said flange sector portions. are flexed to provide a barrier portion with respect to passage of partides and substantially all of the outer periphery of said flange resiliently, engages the inner surface of said envelope supporting said electron gun within said envelope.

3. An electron discharge device comprising a tubular envelope, said envelope having therein a target positioned at one end of said envelope and an elongated electron gun comprising a plurality of tubular electrodes of unitary assembly positioned within said tubular envelope, and

mounted at the opposite end of the tubular envelope with respect to the target, the outerdiameterof said tubular electrodes less than the internal diameter of said envelope thereby defining an annular region, means for centering said electron gun within said envelope and providing a barrier in said annular region to prevent passage of particles, said means comprising a tubular member of resilient sheet metal having a flange portion, said tubular member secured to the outer surface of one of said electrodes with said flange portion extending outwardly from the outer surface of said electrode, the outer diameter of said flange portion being greater than the internal diameter of said envelope, said flange portion having a plurality of radial slits to provide a plurality of flange portions so that when said electron gun is inserted into said envelope, said flange portions are flexed and overlap 5 adjacent flange portions to provide a barrier portion with respect to passage of particles and substantially all of the outer periphery of said flange resiliently engaging the inner surface of said envelope supporting said electron gun Within said envelope.

References Cited by the Examiner UNITED STATES PATENTS 2,055,093 9/36 Wise 3l324l 2,452,620 11/48 Weimer 313-65 2,951,962 9/ 60 Miller et al 313-269 XR ROBERT SEGAL, Acting Primary Examiner. ARTHUR GAUSS, DAVID J. GALVIN, Examiners. 

1. AN ELECTRON DISCHARGE DEVICE COMPRISING A TUBULAR ENVELOPE AND AN ELONGATED ELECTRON GUN COMPRISING PLURALITY OF TUBULAR ELECTRODES POSITIONED WITHIN SAID TUBULAR ENVELOPE, THE OUTER DIAMETER OF SAID ENVELOPE THEREBY LESS THAN THE INTERNAL DIAMETER OF SAID ENVELOPE THEREBY DEFINING AN ANNULAR REGION, MEANS FOR SUPPORTING SAID ELECTRON GUN AND CLOSING OFF SAID ANNULAR REGION TO PREVENT PASSAGE OF PARTICLES, SAID MEANS COMPRISING A TUBULAR MEMBER OF RESILIENT SHEET METAL HAVING A FLANGE PORTION, SAID TUBULAR MEMBER HAVING ITS INNER SURFACE SECURED TO THE OUER SURFACE OF ONE OF SAID ELECTRODES WITH SAID FLANGE PORTION EXTENDING OUTWARDLY FROM THE OUTER SURFACE OF SAID ELECTRODE, THE OTHER DIAMETER OF SAID FLANGE PORTION WHEN PERPENDICULAR TO SAID ELECTRODE BEING GREATER THAN THE INTERNAL DIAMETER OF SAID ENVELOPE, SAID FLANGE PORTION COMPRISED OF A PLURALITY OF RADIAL SECTORS SO THAT WHEN SAID ELECTRON GUN IS INSERTED INTO SAID ENVELOPE, SAID FLANGE SECTOR PORTIONS ARE FLEXED TO OVERLAP AND PROVIDE A BARRIER PORTION WITH RESPECT TO PASSAGE OF PARTICLES AND SUBSTANTIALLY ALL OF THE OUTER PERIPHERY OF SAID FLANGE RESILIENTLY ENGAGES THE INNER SURFACE OF SAID ENVELOPE SUPPORTING SAID ELECTRON GUN WITHIN SAID ENVELOPE. 